In driving simulators, a driver holds a steering wheel and rotates it clockwise or counterclockwise for simulating driving. Driving simulators of this type have been known conventionally. Recently, these simulators adopt generally a structure in which the steering wheel can make one or more revolutions.
As such structure in which the steering wheel can make one or more revolutions, conventionally a structure shown in FIG. 5 is known wherein a first gear wheel 3 with a relatively small number of teeth is attached to a steering wheel shaft 2 to which a steering wheel 1 is fixed, a second gear wheel 5 with a relatively large number of teeth is attached to a auxiliary shaft 4 arranged parallel to the steering wheel shaft 2, and the first gear wheel 3 and the second gear wheel 5 are engaged to each other. In this structure, the steering wheel shaft 2, namely the steering wheel 1 can make one or more revolutions while the auxiliary shaft 4 makes one revolution. The rotation angle of one or more revolutions of the steering wheel 1 can be detected by detecting the rotation angle of one or less revolutions of the auxiliary shaft 4 by means of a detector using an encoding element or other detectors.
In these steering wheel devices, it is undesirable that the steering wheel 1 rotates freely, and thus the number of rotations of the steering wheel 1 is usually limited within a desired range. As conventional stopper mechanisms adopted for limiting the number of rotation of the steering wheel 1, a structure shown in FIG. 5 may be proposed wherein a stopper arm 6 extending perpendicularly to the plane of FIG. 5 is formed on the side of the second gear wheel 5 while a stopper 8 is fixed to a framework 7. In this stopper mechanism, when the second gear 5 rotates and the stopper arm 6 comes in contact with the stopper 8, further rotation of the second gear wheel 5, and hence the steering wheel 1 is inhibited.
Such conventional steering wheel devices present, however, the following drawbacks because both the stopper arm and the stopper are arranged on the auxiliary shaft side that is decelerated by a set of gear wheels. First, the torque applied to the auxiliary shaft 4 increases all the more during deceleration by gear wheels and, accordingly, the load applied to the stopper 8 and the stopper arm 6 may increase enormously and cause them to be broken. Second, the auxiliary shaft 4 may break easily because it is subject at the same time to the transmission load from the gear wheels 3 and 5 and to the reaction from the stopper 8. Finally, the gear wheels 3 and 5 also may break easily because they act directly as a stopper to restrict the rotation of the steering wheel shaft 2 and submit to an excessive transmission torque.
Thus, in conventional steering wheel devices, an excessive load is applied to respective members including gear wheels, stoppers, the auxiliary shaft, bearings supporting the auxiliary shaft or the like. Particularly, it would be necessary to increase the pitch diameter or width of gear wheels or to enlarge the module in order to compensate for the charge to the gear wheels, however, these countermeasures will provoke other drawbacks such as increased cost, loss of a smooth operation or the like.
Now, it is an object of the present invention to overcome the drawbacks mentioned above for the conventional steering wheel devices and more particularly, to reduce the charge on respective components, gear wheel elements to be specific, of a steering wheel device provided with a deceleration mechanism including gear wheels and with a stopper.